Washington DC - A federal judge on Thursday ordered that Kilmar Abrego Garcia be immediately released from detention. In response, President Donald Trump's administration is scrambling for an appeal.

Abrego Garcia's release will come after a year-long ordeal for the Salvadoran man, who was wrongfully deported in March and then returned to the US after months of legal battles – only to face further imprisonment.

A Maryland resident married to an American woman, Abrego Garcia became a symbol for those who oppose Trump's brutal and often violent attempts to round up and detain the country's migrant population.

He was also one of more than 200 people sent to El Salvador's CECOT mega-prison, based on unsubstantiated claims that he is a member of a violent gang.

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The prison is notorious for harsh conditions, abuse, and deaths in custody.

In her ruling on Thursday, Federal Judge Paula Xinis concluded that Abrego Garcia has been held in ICE detention "absent a lawful removal order" and, as a result, must be immediately released.

"His detention has been for the basic purpose of effectuating removal, lending further support that Abrego Garcia should be held no longer," her ruling concluded.

She ordered that the government release him from US Immigration and Customs Enforcement custody immediately while his legal challenge against his deportation moves forward.

In response, Homeland Security spokesperson Tricia McLaughlin accused Xinis of "judicial activism" and vowed to "fight this tooth and nail in the courts."

The Trump administration rapidly scrambled to respond, with White House Press Secretary Karoline Leavitt telling a press briefing on Thursday that they will lodge an immediate appeal.

"The administration opposed this activism from a judge who is really acting as a judicial activist, which we've unfortunately seen in many cases across the country," Leavitt said.